The present invention relates to a manufacturing method of a rocker arm bearing apparatus assembled into a rocker arm that operates to open or close valves attached to a valve train of an engine or like of an automobile.
A rocker arm is attached to a valve train of an automobile engine, and its body rocks about a lash adjuster receiver (pivot receiver) or a rocker arm shaft with the rotation of a valve system cam, thereby operating to open or close the valves of the automobile engine.
A conventional rocker arm bearing apparatus assembled into such a rocker arm includes a pair of opposite sidewalls that constitute a rocker arm body as a bearing holding member, a supporting shaft in which end faces of its shaft ends are caulked on inner peripheral edges of shaft end insertion holes of the pair of opposite sidewalls, and an outer ring rotatably supported on a raceway portion of a shaft intermediate portion of the supporting shaft directly or through a plurality of rolling elements. An external surface of the raceway portion of the shaft intermediate portion of the supporting shaft is hardened by high-frequency quenching. Also, end faces of both the shaft ends are made to have surface hardness capable of being caulked without heat treatment, and thus, the shaft ends are fixedly caulked on inner peripheral edges of shaft end insertion holes of the opposite sidewalls (for example, refer to JP-A-2004-156688).
In the conventional rocker arm bearing apparatus, the supporting shaft is inserted into the shaft end insertion holes of the pair of opposite sidewalls, and after the insertion of the supporting shaft, the end faces of the shaft ends of the supporting shaft are fixedly caulked on the inner peripheral edges of the shaft end insertion holes. In terms of the functions of a bearing, it is necessary that quenching heat treatment is performed in advance in the vicinity of a shaft center portion that is a roller rolling portion of the supporting shaft. However, both the shaft ends of the supporting shaft should not be subjected to heat treatment in order to perform caulking. Such heat treatment of the supporting shaft is limited to local high-frequency quenching using a high-frequency induction heating coil since normal quenching cannot be performed. Thus, there is a problem in that time and efforts are required.